00 00... Transmission (all gears): visually inspect for leaks.
WARNING: This page is about a different car, the 2002 BMW M Roadster, 2002 BMW M Coupe, 2001 BMW M Roadster, and 2001 BMW M Coupe. However, it is still accessible from the selected car via links, so may be relevant.
Inspect visible area of transmission for traces of fluid, remove underbody protection if necessary.